ABSTRACT: We study the production and circulation of arguments justifying actions on the basis of morality. By downplaying externalities, exculpatory narratives allow people to maintain a positive image while acting selfishly. Conversely, responsibilizing narratives raise both direct and reputational stakes, fostering prosocial behavior. Such rationales diffuse along a random network, through costly signaling and strategic disclosure. Norms of conduct and discourse, average compliance, and belief polarization reflect local correlation in types' tradeoffs between reputation and influence concerns. Imperatives (general precepts) constitute alternative modes of moral influence. We analyze the sources of their legitimacy, then their costs and benefits relative to narratives.